Changes in aortic glycosaminoglycans and lipoprotein lipase activity in rats with age and atheroma.

The changes in the individual glycosaminoglycans of the aorta and in lipoprotein lipase activity of the aorta, liver and heart have been studied at various stages in the development of mild atheroma in the rat. Three responses were seen: (a) Hyaluronic acid initially decreased, then increased; (b) Heparan sulphate and chondroitin sulphates A and C initially increased, then decreased. (c) Chondroitin sulphate-B and heparin increased with progressing lipid infiltration and decreased markedly only in the later stages. Ageing changes were also investigated in the rat aorta: total cholesterol, phospholipids and triglycerides increased progressively from weaning to 9 months of age. Hyaluronic acid decreased after weaning, reached a minimum at 6 months and then increased thereafter. Heparan sulphate and chondroitin sulphate-C reached a maximum at 6 months and then decreased thereafter. Chondroitin sulphates A and B showed a similar but less marked pattern of change with age. Heparin progressively increased with age. Aortic lipoprotein lipase activity increased in the early stages of atheroma and then decreased as the lipid infiltration became more severe. The ageing study showed that enzyme activity was quite high at weaning. decreased considerably at 3 months, but thereafter fell only slightly.